algebraic3d

solid box = orthobrick (-3, -3, -3; 3, 3, 3)  -bc=1;
solid electrod1a = orthobrick (0.1, -0.5, -0.5; 0.4, 0.5, 0.5);
solid electrod1b = plane (0.2, 0, 0; -1, 0, 0) and plane (0.3, 0, 0; 1, 0, 0);
solid electrod1 = electrod1a and electrod1b -bc=2;
solid electrod2 = orthobrick (-0.3, -0.501, -0.501; -0.2, 0.501, 0.501) -bc=3;

solid air = box and not electrod1 and not electrod2;


tlo air;

singular edge electrod1a electrod1b;